Intense warming and salinification of intermediate waters of southern origin in the eastern subpolar North Atlantic in the 1990s to mid-2000s

Abstract

Recent thermohaline changes in the layer of intermediate waters (IW) advected into the eastern subpolar North Atlantic from lower latitudes are quantified using the data from the repeated transatlantic sections. Positive trends in temperature and salinity in the IW density class at ∼53°N (0.049°C/a and 0.0088/a; 1992-2002) and ∼60°N (0.044°C/a and 0.0085/a, 1997-2005) are derived. The unexpectedly high rates of the IW warming and salinification cannot be explained solely by the long-term and recent decadal changes at the intermediate levels in the midlatitude North Atlantic and appear to be a consequence of the northward advance of the source water masses caused by the North Atlantic Oscillation-induced contraction of the subpolar gyre. Copyright 2008 by the American Geophysical Union.